Boiler



April 9, 1929.

J. M. MGCLELLON BOILER Filed Feb. 19. 1919 4 Sheets-Sheet l Inventor.'

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April 9, 1929. J. M. MCCLELLQN BOILER Filed Feb. 19. 1919 4 sheets-sheet .3

lnvenov.' Jaws Mjc Clelia,

April 9 1929- J. M. MCCLELLON BOILER Filed Feb. 19. 1919 x4 Sheets-sheet Patented Apr. 9, 1929.

uNi-'TED STATES PATENT OFFICE.

JAMES M. IVICCLELLON, OF EVERETT, MASSACHUSETTS; HAROLD B. MCCLELLON AD- IVIINISTRATOR OF SAID JAMES' M. MCCLELLON, DECEASED.

BOILER.

Application filed lFebruary 19, 1919.

my invention I shall refer specifically to locomotive boilers. This application constitutes a continuation in part of my earlier copending applications Serial No. 2,565, led Jan. 6, 1915, Serial No. 101,610, filed June 3, 1916, Serial No. 122,754, filed Sept. 28, 1916, Serial No. 134,897, tiled Dec. -1, 1916, and Serial No. 175,088, filed June 16, 1017, and generic claims covering the subject matter of invent-ion disclosed in said applicat ns and also exoinpliiied by the particular structure here described are herein presented.

My invention will best be understood by reference to the following description of the illustrative embodiment thereof taken in connection with the accompanying drawings wherein z Figure 1 is a rear end elevation of the fire box;

Fig. 2 is a contrai longitudinal section showing portions ofthe fire box, combustion chamber and barrel;

Fig. 3 is a section, on an. enlarged scale on line of Fig, 2;

Fig. 1- is ical diametrical section through a iire bei; tube illustrating the manner of shaping it,

5 and 6 are end views of bottoni of such tube;

Fig. 7 a detail, partly in section, showing` a fire box tube and a portion of the crown te which it is connected;

S is a perspective detail of a pair of box tubes and fragments of the foundation chamber and crown;

F 9 is a section on enlarged 4scale 9 0 of F 2; and 1g. 10 is a longitudinal section through 'he throateliamber and part of the foundachamber substantially on the plane of he line 10-10 of Fig. 3.

Referring in detail to the illustrative embodiment of my invention shown in the acconipanying drawings by way of example, the general construction may perhaps be the top and Serial No. 277,968.

most clearly understood from Fig. 2 wherein I show a barrel 11 whicln with exceptions which will. be readily understood as the' descript-ion proceeds, may be of the type customary in locomotive boilers. Vithin this' barrel and' closing the lower portion thereof a flue sheet 13 which in the present case iis spaced inwardly from the rear end of the barrel for some distance to provide a combustion chamber, as hereinafter described. Flues 15 open through the flue sheet and cX- tend forwardly tl'irough the barrel in well known manner.

The upper edge ofthe tine sheet 13 may be provided with a` flange 17 adapted to fit the Y lower portion of a suitable crown chamber forming a part of the fire box and to be riveted thereto, as shown. While the crown chamber may take various forms, I prefer to construct it, as shown in Fig. 3, ofa number of substantially cylindrical drums of inherent pressure-resisting forni; and l have herein shown a central drum 10 and smaller lateral drums 21. The sides of the several drums may be somewhat flattened', as 22, and securedtogether, the central drum 19 fitting l'setween the others in the manner of a keystone.

The forward ends of the drums arc open and are received by the opposed open end of the barrel, and I prefer to have these drums lit the saine and completely close the upper segment of the barrel above the flue sheet 13 which itself is disposed wholly bclow the crown. To facilitate this, the end portions of the drums may Ybe somewhat distorted from true cylindrical. form, providing extruded portions 23, Figs. 1 and 3, having flat sides so that the ends of the drums fittogether block-like to form, collectively, a segmental structure adapted to fit the open end of the barrel 13 and which may be riveted' thereto. Preferably also, the drums are providedl with similar eX- truded portions 25 (Fig. 3) at the lower aortions of the forward ends, providing a substantially straight-edged marginal portion against which the flange 17 of the fiue sheet may fit. In other words, inr the preferred construction shown, the main body of the crown Ais formed of substantially cylindrical and therefore inherently pres sure-resisting parts, as shown in Fig. 3. 1t

will be understood, of course, that the pressures on the flattened portions 22 arebah anced.fThc forward end of the assembly, however, is in form a segment of the circle formed by the end of the barrel. The rear ends of the drums as best shown in Fig. l, may also be provided with similar extruded portions 2T at the bottom side thereof nrovidino" a substantiall straight! edged portion to which the tubes forming the rear wall of the fire'box may be connected. The rear ends of the drums may be closed by suitable heads 29 conveniently dished, as shown in E2, to resist pressure.4

' a space within the end of the barrel and rearward of the tube sheet, bounded by the segmental extension of the barrel and the forward portion of the crown, providing for y a combustion chamber hereinafter to be described.

rlhe walls of the lire box are formed of comparatively thin-walled, wator-rcceiving tubes of inherent j n'essure-resisting form. In other words, the tubes are, at least throughout the major vportion of their length, cylindrical,y thus offering a large heating surface to the lire while providing a structure of great strength as regards internal pressure. The various details of construction which l shall hereinafter describe are designed to permit tubes to be used in the most advantageous manner to provide unbroken, smooth-surfaced, water-containing walls for the lire box, not .subject to burning out and corrosion and formed to facilitate a regular circulation of water in one direction from the barrel through the tubes to the crown chamber.

' l shall irst describe the construction of the side walls of the lire box proper, after which the construction of the rear wall and of the water-containing wall of the combustion chamber, as herein shown, will be more readily understood.

The side walls of the combustion chamber 'as stated, comprise (see Fig. 2) a number of thin-walled tubes V having cylindrical body portions set substantially l inv contact side by side and extending substantially vertically between the crown drums 2l and a bottom chamber 37 which supplies waterto the tubes.

I have herein disclosed a bottom chamber 37 as formed of a cast steel mud ring 39 to which are secured plates ll forming an openvrel, as shown best in Fig.

topped, channel-shaped chamberin which may be braced at the open side by stays d3. Conveniently the mud ring 39 may be made of a greater width than is customary in standard boilers built of sheets, so that the bottom chamber 3T may be of generous size to supply plenty of water to thelower ends of the tubes 35. Y

vTo carry water from the barrel to the bottom chamber 37, the latter opens into a throat chamber thebottom of which may be formed by the forward transverse portion of the mud ring 39. A throat sheet extends between they inner plates' ll upwardly from the rear side ofthe mud ring and overlaps and is riveted to a reduced edge portion 47 of the barrel 1l.' I prefer to make the sheet 45overlap the barrel, as thus the lire. plays on the face of the relatively thin sheet 45 the opposite face-ofwhich is cooled by water, whereas if the barrel shell lay on top the projecting endportion of this comparatively heavy plate, Alying rearwardly of the rivets andnot in direct contact with water, would be subjectr to the heat of the fire playing on the edge thereof andmight well be lire-cracked. Cooperating with the sheet 45 to form the throat chamber is a sheet 49 secured to the forward side of the transverse portion of the mud ring, the two sheets extending upwardlyalong the sides of the barrel, as indicated in Fig. 3, and secured together at the sides, the transverse form of the throat chamber approximating the form of the lower portion of the fire box, as indicated in Fig. 3. As shown at the right hand side in that ligure, closures 51 may bewelded in place between'thesheets and to' prevent trapping of steam -in the corners thus formed, pipes 53 may connect these upper portions of the throat Vchamber with the crown drums.

l/Vater is supplied to the throat chamber through a passage formed by a sheet inarginally secured to the under side of the bar- 9, and having a closed end (Fig. 2) extending forwardly of the flue sheet 18 and overlying an opening 57 in the barrel, and an vopen end embraced by a flange 59 of the sheet 9 and thus conimunicating with the throat chamber. The throatchamber and passage are suitably stayed,vas shown. It may be noted in passing that the stays just referred to are practically the only ones necessary in my improved type vof boiler; and it will be noted thatgthese are substantially all out of the zones of highest heat and less subject to damage than the multitudinous stays customary in a standard boiler, many of which are subject to the highest heat. 'For example, the sta-ys of the passage 55 are'exterior of the barrel and their inner ends are protected by the water-containing tubes of the combustion chamber', as hereinafter to be llO meegenodescribed. The stays of the throat sheet and the sta-ys 4l of the foundation chamber are not in the regions of greatest temperature.

ItV being assumed thatV the passage and the bottom chamber 37 have been made of such proportions as to assure an ample supply of waterbeing drawn rearwardly from the barrel, the next problem is to permit the water to pass from the bottom chamber through the tubes without hindrance and also to provide a substantial. connection bet-ween the bottom chamber and tubes in a construction which will provide an adequate water-eontaining, retaining wall for the lire within the tire box and will not be subject to undue corrosion or to rupture.A Herein the ends of the tubes are received by and completely close the open upper side of the foundation Vchamber and this may be effected by providing the wall of tubes with a flatsided marginal portion on which the side plates il may lap and be secu-red. In the present instance I attain this by the construction bestshown in Figs. 8 and 6. As there indicated, while retaining the cylindrical, pressure-resisting form of the body por tions of the tubes, which permits me to make them both thin and strong, I distort the lower ends by pressing them out square, as shown at 6l, the side of the square being equal to the diameter of the cylindrical body portion 35. When a series of these tubes is set side by side, with the cylindrical body portions in contact, the flat sides of the portions Gl will lit together viny the manner of blocks, as illustrated in Fig. 3, and form an uninterrupted marginal portionfor the wally which in itself will have flat sides formed by the aligning iiat sides of the squared end portions 6l. This flat-sided marginal portion ofthe wall is adapted to be received between the channel flanges Il formed by the side plates of the bottom chamber andv completely to close the open side of this cham; ber. The plates Lll are secured to the flatsided marginal portions referred to by lines of welding 63 (Fig.

To seal the joint between abutting squared end portions of the tubes, I may somewhat depress the meeting faces, for example by driving a suitable tool between the same, to form a recess, as indicated at 65 in Fig. 2, which recess is thereafter filled up by metal welded into place.

Hitherto one of the major diculties of constructing locomotive fire boxes with water-tube walls, a difficulty illustrated by my own efforts as shown by'my various patents in this line, has been the joining of the tubes to the bottom chamber with a view to provioing a connection of adequate strength without undesirable breaks in the wall and one which would permit the passage of sufficient water without throttling it or checking its head by successive constrictions and enlargements of the passageway. The construction` herein admirably meets all conditions. It will be noted that the main portion of Athe wall is composed of tubes of cylii drical, that is, of inherently pressure,- res ting form which are set side by sidev and preferably in contact. At the same time there are no interstices at the margin of the wall where it joinsl the bottom chamber, which intcrstices would have toy be plugged up, but the fire box wall to and including the bottom chamber where exposed to the lire is composed of the thin walls of the tube backed by water and substantially in contact one with another to form: an unbroken contai-nev1 for the r'ire. The structure is, furthermore, particularly adapted to construction by the use of the welding process` and bv utilizing such process I do away with all projecting stay heads, rivets and the like which would invite incrustation and which would be likely to be burned cti. It will furthermore be noted that the opening from the bottom chamber to the tube is uninterrupted and is substantially large as 'the bottom chamber itself. It follows that no impediment is placed upon the upward passage of water through the tubes but that the circulation through the lire boX is facilitated throughout.

I shall next describe the manner in which the upper ends of the tubes are connected to the crown drums to communicate therewith. Hereinprobl'ems similar to those encountered where the tubes join the bottom chamber are found, which problems are also intimately bound up with the former ones since, for example, the provision for ample communication between the tubes and the bottom chamber would be, comparatively speaking, of minor importance were thc passage of water to be checked at the tops of the tubes.

As best shown in Fig., 7, the end portions of the tubes may be inwardly bent somewhat, so that the ends of the tube wall are presented substantially perpendicular to the wall of the drum 21. To secure the tube 'to the wall, the end thereof is preferably drawn out of shape, in the manner best shown in F ig. 5, not to the square form (il of the bottom end of the tube, but to an oblong and preferably rectangular form, shown at 67 in Fig. 5, the longer dimension of the oblong being transverse to the wall formed by the totality of the tubes 35 and transverse to the longitudinal anis of the drum 2l with which theftubes communicate, as best shown in Fig. 8. rl`he eiiective area of the oblong opening thus provided is, of course, somewhat smaller than the area of the circular cross section of the tube. As it is impracticable for reasons which will appear to utilize the end of the tube in its original circular form, I may so proportion lOl and thedruni wall.

the. rectangle as to obtainY the necessary opening while retaining` certain advantages hereinafter to be referred to. The distorted end portions 67 of the tubes 'inay merge into the tubes along a curved line (59 7) corresponding to the curvature of the drum 2l; and the ends are inserted through suitablyl formed rectangular openings 7l in the drum and inay be trimmed off, as indicated in Fig. 7,`to the curvature of the interior of the drinn. The portions 67 are united to the drinn wall by interior lines of welding 73 and, if desired, by exterior lines 75, the lines of welding T3 providing va-pressure-resisting joint betwe n the tubes rlhe structure not only adapts itself to the use of welding but in sible only in a welded structure since, for example, the rectangular vtube end could not be expanded or beaded-over or conveniently connected in any simple manner.

By the provision of the oblong openings 71 in the drum wall, the longer dimensions of which are transverse to the axis thereof, I provide for a communicating passage bot-fween each tubev 35 and the drum which is as nearly as practicable the full size. of the tube; and by connecting the tubes in the manner just described this passage not in any way obstructed. At the saine time, as

shown best in Fig. 8, there intervenes between adjacent openings a body of metal 7G of substantial width and strength; and in virtue of the manner of connection described, this body is not weakened by any holes or openings giving` Vrise to narrow necks of metal likely to rupture.Y

- Since the body portions of the tubes are set side by side in contact in the ire box wall, they could not be carried up into the crown drinn side by sidebecause a Zone of the crown drum would be completely cut away. lf the tubes were tapered or reduced in diameter, as has been attempted, the ta-Y pering', in so far as it provided for suliicient space between the openings in the crown drinn to provide adequate strength, would equally contract and choke down thetube, obstructing proper circulation in the boiler. By elongating the openings transversely of the axis of thel tube, as described, a coniparatively thin-walled drum 2l may be used, with obvious advantage, while retai ing ainple strength between the openings 73 which, moreover, are of large area, approxin'iating` the cross-sectional area of the tubes 35 themselves. rlhe connection herein described necessitates a slight opening between adjacent tubes where they. join the crown drum which, however, is negligible as contrastedV with the simplicity of the structure.v

it will be noted that the connection of the parts is most convenient, since a man can readily enter the crown drum 2i, the

interior of which is not obstructed by any stays or braces whatever, and apply the welding 73 around the margins of the tubes, which weldingr not only holds them in position but forms an absolutely water-tight connection.- A `I The constructions of thek ends of the side wall tubes, herein described, besides thei functional cooperation alreadyy referred to, are such as to facilitate formationy of the tribes which may readily be efected-in the manner illustrated in Fig. 4r. The straight cylindrical tube, before being bent in the manner indicated in Fig.l 7, may'A have its ends formed by ineens of `a die or form 77 corresponding tothe internal 'href the lower end of the tube, as shown in Fig. 6,

and another collapsible forni '79 having-a cylindrical base portion 8l from which central'portion 83 to which are Vdela hably secured sidey pieces 85, trie parts S5 and 85 having the Vgeneral formation of the upper end of the tube, as shown in Fig. t. 'lhe two forms may be held in alignment by a rod 8i' sliding in the form T7. To shape the tube- 35, it is placed with its end portions fitting over the cylindrical portion 8l of the upper form and the cylindrical upper portion of the lower form, and the two are then lpressed toward' each other. This serves to press out the lower end ofthe tube tothe forni shown in Fig. 6,-and the upper end of the tube is ressed outwardly at the shorter sidesjof the oblong shown in 5 at the saine tiniedrawing inwardly a f at "le longer sides which extend transversely .ri-ling'.` 4. In this action the Ymetal itself is little strained, the change being principally one of shape. Byl a single operation, which may be performed on the tube when cold, it is thus formed ready for bending with the exception of` pressing down the sides of the oblong extension at (39 to fit the shoulder of the die, thus 'adapting itto the shape of the crown drum. rEhe pin rsecuringthe portions and of the upper col-V lapsible die 79 may then be withdrawn and the tube freed, ready for bending.

ils seen in Fig. 2, certain of the side wall tubes SSadjacent the foi-.vard end of the boli will align with. the throat chamber rather than with the foundation chamber 3i'. These may be connected to the crown in the manner already described for the side wall tubes 35. Their lower ends are preferably bevelled to conform to the inclination of the 'throat sheet 45 and enter suitable apertures in the same to the margin of which they are welded.

The rear wall of the lire box, as shown in Fig. l, may be Vformed of tubes 89 substantially similar to the tubes 35. To provide a larger grate surface it is desirable to permit a certainfupward taper of the wall, as illustrated in Fig. l, and therefore the Vwall tubes are secured to the tubes themselves may be slightly tapered. It is also unnecessary to bend the4 same, as the tubes 35 are bent in the manner indicated in Fig. 7. The extrusion of portions of the, crown drums at 27 provides 'a substantially continuous, `fiat-sided portion in which the oblong` lnecks of the tubes may be entered aud secured in the same manner that the side sides of the drums. Similar advantages iin providing ample space between the openings in the drums are found in th'e case of the rear 'wall tubes.

To provide an opening for a re door, I 'do not use tubes extending from the bottom chamber to the crown at the middle portion o-f the rear wall, but at a suitable height for the upper edge of the door opening' l insert a channel 91 (Figs. 1 and 2) marginally welded to two laterally placed tubes 89, which tubes may have openings 93 (Fig. 2) cut in the wall thereof providing communication with said channel. Shorttubes 95, secured to the crown drum 10 in the saine manner as the longer tubes 89 are secured lto the crown drums 21, are provid-ed, which tubes may have lower squared portions formed in lthe manner illustrated in Fig. 6 and similar to the lower 'ends of the other tubes,` which portions are fitted into the channel 91 in the same manner as the other tubes are litted into the bottoni chamber. 1n the present instance have .shown the space between the bottom chamber and the lower edge of the door opening as filled with lire brick or tile 97. 1

Preferabljqthe rear wall of the fire box slopes forwardly from bottoni to top, as illustrated in Fig. 2. To complete the inclosure, ay suitable number of blind-ended tubes of appropriate length, as for example 09and 101 shown in Fig. 2, may be provided, these tubes fitting the bottom chamber in the same manner as the other tubes. Suitable openings 103 through the contacting' walls of adjacentI tubes provide communication between these blind-ended tubes and adjacent tubes which reach directly to the crown.

I have herein (see Fig. 2) shown a baille VWall 105 of tile, supported on arch tubes 107 opening `at one end through the'throat sheet 15 and at the other end expanded into certain tubes of the rear wall. i To facilitate the connection of the arch tubes 107,-the portions of thetubes with which they connect may be squared, as indicated at 109. below the oblong` necks 111. At the outside rear wall of the lire box oppositethe ends of the arch tubes, plugs 113 may be inserted .in the flattened surfaces to facilitate cleaning of the arch tubes. To permit the eXpansion of the ends of the arch tubes and the insertion of the plugs, the front and rear flattened faces may suitably reinforced,

either v'by slightly upsetting the tube or by welding on extra metalmaiginally of the openings.

The boiler here inllustrated also embodies in its construction ja combustion chamber including` water tubes housed within the seffmental extension 33 of the barrel. As seen in Fig. 3, these tubes 115 are curved to the form of the interior of the barrel. The upper end portions are provided with oblong necks 117 similar tothe portions 07 of the tubes 35, illustrated in F and are entered through the wall of the crown drum in analogous manner, as will be clearly understood by Fig. 2. The body portions of the tubes conform to the contour of the extension 33 of the barrel shell, but are preferably slightly spaced therefrom to permit free movement in expansion land contraction. The lower ends 119 of the tubes are .presented in Opposition adjacent the lower median line of tlr barrel and means are provided whereby they may be pla-ced in communication with the water passage beneath the barrel shell, one suitable manner of 'effecting the purpose being bestillustrated in Fig. 9. Preferably, the ends 119 are squared, as shown, to fit together block-like and give a yiat-sided marginal portion which will rest firmly on the inside Vof the barrel. Closures 121 may be welded in the ends of the tub-es which are'thus blind-ended, and to Vprovide communication with the chamber 55 nipples 123 are welded into the lowermost squared side of the tube and pass through the barrel shell extension 33 and open to the passage 55. Suitable plugs 125 are provided in the opposite flattened sides, opposing the nipples, to facilitate cleaning. The welding ,securing the closures 121 in place may be extended at the lower side at 127 to secure the 'ends of the tube to the barrelshell, which will relieve the nipples 123 of strain through expansion or contraction.

It might be considered that the adoption of the construction just described tends to stultify the statements made concerning` the importance of the nia-nner in which the ends of the side walltubes 35 are connected to adjacent parts. The conditions in the case of the combustion chamber tubes are, however, markedly different since the barrel shell 33 is much heavier than it would be desirable to make the crown drums and consetpientlyk the round openings can be placed much closer together without undue weakening. Moreover, the combustion chamber tubes are not subjected to the racking strain to which the side wall tubes are subjected in lthe travel of the locomotive. since they are housed by and supported by the heavy barrel shell and by the three crown drums fitting together in the manner of an arch and securely fastened to the barrel shell by the so-called splice joint, illustrated in Fig. 2.

- to where Athey are joined together and can Vmake a quick and workmanlile Job of the f Conveniently, the lower ends 119 of the combustion chamber tubes are somewhat spaced, as shown, which will facilitatoreplacement of sections. The space between them may be lled With tile 129, the purpose being'chiefiy to prevent deposit, since the extension 33 of the barrel shell beneath the space is cooled by the Water in the passage 55, Through the features of construction described and their joint and cooperative effect,

I provide a locomotive lboiler having manyV advantages over the present standard type wherein the fire box is formed of spaced sheets ,secured by stay bolts and rivets, and having many of the advantages claimed for the best types of stationary and marine water-tube boilers.

The most striking advantage of a locomotive lire box constructed asdescribed consists in the practically complete elimination of stayed surfaces which are in every w-ay undesirable, being not only unsatisfactory as a construction initially butdemanding an excessive amount of repair on account of failure of stay'bolts which are loosened or broken by the expansion and contraction of Vthe parts and the pounding strains caused by the travel of the locomotive. herein provide, in place of fiat surfaces which must ynecessarily be stayed, small strong parts which may be made of thin material of high thermal efficiency but Vof such form as to be of great strength without reinforcement by stays. In the event of damage to any ofthe parts, they may easily be repaired or rei placed without interfering with the remaining parts, and it will benoted that in the construction described all are very accessible aiid a workman can readily have access repair.

While ,providing a. conveniently assembled and conveniently repaired structure, I

Yat the same time forni a. fire box wliei'ein the metah which in either eventniight cause leakage. On tliccontrary, separate parts are practically entirely eliminated and projecting portions reduced'to a minimum, so that the fire box presents within and without smooth regular surfaces readily cleaned and affording little opportunity for the lodgeinent of dirt. Y n

Besides these features, which relate more particularly to the building and upkeep of the structure, I obtainthe important func- -structure -Would encounter in use, unless tl walls thereof were'made-unduly thick, in

Lacasse tional advantage of providing ai'egular and steady circulation of water in the boiler which increases the steam-generating efficiency and at the same time lengthens the life of thel boiler since" the parts are kept at y Vllie water in the fire box is divided by the wall tubes into comparatively small columns, and a half of the perimeter of these columns is directly subjected to the heat of the lire i 7ith only a thin wall of metal intervening. The column of water is t-hus readily heated and can rise as a unit toward the crown. rTic column, moreover, is not so lara'e as to introduce conflict-ing currents, causing priming by motion of steam up through dca practically constant temperature.

scending column of water; but sincean ample intake is provided at the lower ends of the tubes and anr ample enit at the upper ends, a continuous and steady motion of a practically uniformly heated stream of water iS provided for. i

In order to obtain a proper rigidity of construction while keeping the lwalls ofthe water tubes of sufficient thinness to provide eiiicient heating surfaces, the tubes should be ofV fair size. llVhile I do notl wish to be limited to any particular dimensions, I believe that for tlie'present type of locomotive a tube about 6 in diameter and of-'about 8/16 *all is suitable and that this diameter of tube is practically the Vmaximum which 'can advantageously be used. Very small tubes would not have `su'flicient,strength to withstand the racking' strains which the -e which case they would be ine'llicient and likely to clog up; but by using a comparatively large tube the necessary structural strength is obtained and the walls may be made thin so as to obtain high absorbing efficiency. At the saine vtime the tubes are notof such size as to permit the travel of relatively warmer and cooler currents of wateifin opposite directions therein, but the column of water ispermittedto move up- 'wai'dly yas a unit. This is facilitated not only by the thin wall of the tube butV by the fact that such alarge proportion of its surface exposed at the interior of the lire box.i fi marked increase in the size ofthe tubes, besides unduly encroachiiig upon the grate space, would tend to forni too lai-,ge passages in which the warmer water would travel upwardly on the inside of the fire box and cooler water downwardly at the outside. In fact. I have some reason to believe that even Vwith a G tube theslight reduction in area of the upper end thereof, caused by its distortion from a circular to a rectangular forni, as shown in Fig. .5, is not without advantage. By thisI mean not without advantage apart fromtlie question ofpreserving the strengthofthe" crown drum and permitice llO

ting that drum to be made or" thin metal. The slightly restricted outlet tends to pre- Water to thc tubes ot' the fire box Wall. The Water moves thence in a regular detcri. 'ned direction of circulation upwardly through the tubes, Without any interference to rising currents, and since the tubes divide the Water into comparatively small streams, there is no tendency for 'the development therein et reverse currents cooler vv t from the crown; but on the contrary the water, atter having' disengaged the sceam therefrom in the crown, will pass in a lar circulating iloiv to the barrel and o back through the foundation chamber and up through the lire bof; tubes in the mapner already described. From the -toundation chamber the water is delivered to the t through the squared ends ,1.N i robs shown in u G. The intake ends of the tubes provided by these squared portions 1`resent an area pra-ci tically, as large as the plan area ot the foundation chamber itself and Alully as t as the combined cross s etions et the tubes. There can thus be no question et' supplying the tubes with ample Water to permit an upward Vcirculation therethrough and the head et the column is not diminished or throttled down in any wav. The delivery openings 7l, shown in Fig. S, are also large and the column is Vthus not held back in such a Way that priming might ensue, but passes readily to the crown drums. PT'- passed upwardly through the tubes, the wir ter and steam find in the crown drum an ample Water space With a large surface trom which the steam can be disengaged at a high temperature and without foaming. The communication et this crown with the barrel is suon that the Water level and the pressure on the Water are ecuialised.

The regular circulation iz'ater Vmade possible by the combination ot parts described provides for most eiicient heating and for liberation et the steam in a dry state. In the ordinary or standard boiler Vhaving side legs, the circulation is retarded since there are current-s et steam and Water moving upwardly and other currents ot cooler water descending Within the same Water space, these currents struggling and scrubbing against each other and being` continually shifted in direction by the stay bolts. The motion of the Water throw 1 the tire be); is thus slaelrened and retar l so that the heat the lire not abstracted with desirable rapidity and the steam engaged in the crown is highly saturated, Theseobjcctions are overcome in the prest case, since the chamber at the lower end the side sullicicntly lar to supply water o die tubes; and the upper deliyery ends et the tubes, While so smul as to checl: the circulation, o suhioient arca to be entirel'-.7

ascending curro; ot mi k` viator, thus assuring a preeeteri d posit \e cnculation in one dnecti n. ,ly thrJ circilation a ra' .=d met ement is dieeten finch utilizes the heat et the ire most etso that it is exhausted from the stach at relatively low temperature and dry and highly eilicient steam is disengaged in the eren n. ng described in detail the illustrative embooiment of my invention own in the drawings, the yninciple' ercby in what I now con der 'l e, altlio 1 not immutaole, rali attempt to deline in the tolms:i Y er lirebox comprising in combinaitudinal chamber and a longitudinal Water-containing Wall comprising a plurality of tub having cylindrical body portions set closely together side by side, the ends of the tubes being shortene(4L l.' tudinally and ex' nded transversely to provide elongated, spaced dis-."harage portions ont capacity approaching that of the tube body, said portions entering correspondingly shaped openings in the chamber wall and secured therein.

2. As an element tor boiler construction, a thin walled, cylindrical tube having' an end portion extended across one diameter and inbent across a conjugate diameter' to provide a neck portion of substantially rectangular section. Y

3. ln a: boiler' in combination, a barrel, a flue sheet therein, the shell of the barrel ntending rearwardly beyond the ilue sheet to provide a combustion chamber, Water tubes housed in the barrel shell and lining the Walls ot' said chamber, a plate secured to the bottom of said barrel and co-operat ing with the shell thereoi` to provide a chamber communicating with said barrel forwardly ot' the due sheet and means providing for communication through the barrel shell between the interior ol"v the latter chamber and said tubes.

In a boiler, a barrel,a iirebox having Water-containing spaces. a bottom chamber extending from said barrel and in communi cat-ion With the same and With the Watercontaining soeces ot said irebox, and a com` llO bustion chamber between the barrel and lireboX having` walls comprising tubes having opposed blind ends overlying said bottom chamber and openings through the sides of said tube ends atilording communication with the bottom chamber.

5. In a boiler, a barrel., a iirebozi having water-containing spaces, a bottom chamber extending from said barrel and in communication with the same and with the watercontaining` spaces of said iirebox, and a combustion chamber between the barrel and lireboX having walls comprising tubes having opposed blind `ends vhaving` attened sides iitted to the upper wall of said bottom chamber and openings through said sides and said wall affording communication with the bottom chamber. Y

6. In a boiler, a barrel, the lower portion thereof being rearwardly extended, means cooperating with the extending` portion to form a bottom chamber of which said portion forms the upper wall, a crown cham- Y ber secured to said barrel, means cooperating therewith to form a Iirebox, and a combustion chamber between said tirebox and barrel having walls comprising tubes extending froin said crown chamber and having blind ends overlying the extended portion ofthe barrel, there being openings through said portion and the lateral walls ofsaid tubes providing communication between said tubes andthe bottom chamber.

7. In a boiler a barrel and a throat chamber comprising a trent sheet secured to the under part of the barrel shell and a rear sheet having its edge extending over -the rear edge of the shell, overlapping' and secured to the interior surface of the same Awelded thereto,and Vapertures in said sheet permitting communication between said tubes and the space beneath said sheet.

9. In a boiler, a barrel and a lirebox, there being an inclined throat sheet extending between said barrel and tirebox, wallsitor said virebox comprising alplurality of uprighttubes, certain of said tubes engaging said sheet and having their ends beveled to contormto the inclinationthereof, said sheet having apertures therein correspond ing to the section of said tubes, the margin oi said apertures and the extremities of the tube walls being welded together.

l0. A boiler comprising a barrel, a crown chamber opening'into the upper portion of the barrel, a transverse throat chamber opening into the lower portion thereof, rebox walls comprising hollow sections opening at one end to the crown chamber and at the other in communication .with said throat chamber and exteriorly disposed pipes extending between the upper lateral portions ot said throat chamber and the crown chamber to permit the escape of steam from the throat chamber. p

' In testimony whereof, I have signedemy name to this speciiication.

JAMES M. MCcLELLoN. 

